Telephone system



Aug. 8, 1939. E. s. PETERSON I TELEPHONE SYSTEM Filed Dec. lO, 1957 3Sheets-Sheet 1 EDWARD S. PETERSQN ATTORNEYS.

Aug. 8, 1939. E'. s. PETERSON 2,168,880

TELEPHONE SYSTEM Filed Dec. lO, 1957 3 Sheets-Sheet 2 EDWARD S. PETERSDNBYww' M,

ATTORNEYS.

Aug. 8, 1939.

lO, 1957 3 Sheets-Sheet 3 Filed Deo.

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vmm 0mm Oom mmm mm M .mu-n- HVVQVDR. EDWARD 5. PETERSDN BY M, afmy MATTORNEYS Patented Aug. 8, 1939 UNITED 'STAT-ES r' PATENT O FF I CETELEPHONE SYSTEM Edward S; Peterson,

Elmwood Park, Ill.,y assignor Application-December 10, 1937, Serial No.179,124

23 Claims.

The present invention relates generally to-signalling systems and hasfor one of its objects the provision of an improved telephone systemadapt- Ved for use on a train vcomprising a plurality of cars orvehicles.

The utility of providing telephone facilities on av railway train forcommunicationV between the various cars has been recognized for sometime and, as a result, telephone apparatus has been provided as standardequipment in the constructionof the railway cars of recent design. Oneof the chief points of utility infproviding a system of this characteris that of kenabling the engineer in the locomotive cab to be'advised bymembers Vof the train crew as to the condition ofthe train fromtelephone stations located at strategic points incertain of the'cars ofthe train. VSpecically, the greatest use islfound in switchingoperations wherein a trainattendant may relay information over thetelephone system to the locomotive engineer from a telephone stationlocated at the rear Aof the rear car, thereby to control movement of thetrain in a rearward direction. As is wellknown, it is frequentlynecessary to provide two locomotives on trains which are heavily 'loadedand which are required to travel over routes having highly gradedvroadbeds. Inthis type'of train, it isihighly desirable that telephoneequipment be provided such that communication may be had between the twolocomotive cabs and between each of the cabs and other telephonestations located in the other cars of the train. Trains are usually madeupby the train crew prior to each run and no set rule is followed asregards the particular cars which will make up the train in any givencase or the manner in which these cars will be arranged. This isparticularly true with reference to the manner in which the twolocomotives of a double-header train are connected for use. By Virtueofthis indiscriminate mode of assembling the 'cars making up a train, theproblem is raised of'providing a telephone system wherein the telephonestations may be connected in a variety of ways to form a uniied systemand wherein the mode of operation of the system is the same irrespectiveof the arrangement of the component stations.

It is a further object of the present invention! therefore, to providean improved and exceeding- .ly simple arrangement whereby communicationfacilities are provided between the cab of either of two locomotivesofadouble-headertrain and other ltelephones located in the other cars ofthe train, andv also directly between the Vtwo cabs,Y and whereintheapparatus in each cab is so arranged that the locomotives maybe'disposedin any-de sired order without disturbingthe communicationfacilities.

f More specifically, it is an object of theinvention to providetelephone equipment of improved and economical arrangement for use onavehicle, such, for example, as a locomotive cab, which may be connectedina telephone system in'anyone'of a number of ways toprovidecommunication facilities for the vehicle rand wherein the modeof` operating the equipment is the same'irrespective ofthe mannerin'which the equipment-is connected in the system.

In the speciicembodiment of theinvention de- 'scribed hereinafter,lthere are provided a plu- `15 rality of telephone stationsrespectivelyv located onr certain `of the several vehicles makingup arailroad train, which stations are interconnected by a lline circuitcomprising av plurality of conductors. Two telephone stations arelocated Vin each of the `two locomotive cabs embodied inthe train Yandone station is provided-in eachv of cer- -tainofthe other cars equippedfor telephone service. The equipment at each station comprises atelephone transmitter and receiver normally'disconnected from the linecircuit and a' manually operable switch operative to connect theassociated transmitter and receiver tothe circuit. Since the primarypurpose of the system is to provide facilities for transmittinginformation to the'engineer, a signal device is only provided at one ofthe stations located in each of the locomotive cabs. The arrangement issuch that the signal devicev provided at'the one station in each 'cabmaydirectly be energized through the operation of a manually operableswitch provided at the other station located in the same cab over acircuit independent of the line circuit, or itmay be energized inresponse to the operation of a manuallyoperable switch provided at oneof the 40 stations located in the other locomotive cab. As regards theenergization of -thesignal devices on calls initiated at stations otherthan the locomotive Vcab stations, means are- -provided responsive tothe actuation of a manually operable switch at one of these otherstations for causing the simultaneous energization of all of the signaldevices. When such a call isanswered at one of the stations in one ofthe cabs, control apparatus is caused to operate to cause thedeenergization of all of the signal devices. By this arrangement themethod of signalling is rendered selective as regards calls between thecab stations, but is nonselective on calls originating at a stationother than a cab station.

The novel features believed to be characteristic of the invention areset forth with particularity in the appended claims. The invention, bothas to its organization and method of operation, together with furtherobjects and advantages thereof, will best be understood by reference tothe specication taken in connection with the accompanying drawings, inwhich one embodiment is illustrated. In the drawings, Figure 1illustrates the apparatus provided at the two telephone stations locatedin the cab of the rst locomotive of a double-header train, Fig. 2illustrates the similar apparatus provided at the two stations of asecond locomotive, and Fig. 3 illustrates the apparatus provided,respectively, at two telephone stations located in two different cars ofthe train following the two locomotive cabs.

Referring now more particularly to the drawings, there is illustrated animproved telephone system which is particularly well suited for theapplication mentioned above, namely, on a train comprising a pluralityof Vehicles, at least certain of which, such, for example, as thelocomotives, are interchangeable. In brief, the system comprises aplurality of telephone stations |00, |50, 200, 250, 300 and 350interconnected by a line circuit divided into sections |04, 204, 304 and301. As indicated in the drawings, the two stations |00 and |50 arelocated in the cab of the first locomotive of the train, the twostations 200 and 250 are located in the cab of the following or secondlocomotive of the train, the station 300 is located in the baggage car,and the station 350 is located at the rear of the rear car, which lattercar may be the observation car of a passenger train` or the caboose of afreight train. The enumerated sections of the line circuit extendbetween the several cars and terminate in voice frequency currentrepeaters. Thus, the line circuit section |04 comprises a pair ofconductors |05 and |06, respectively connected to the terminals of onewinding |9l, |92 o1" a repeating coil located in the first locomotivecab at the station |00. The conductors of this pair are also connectedto the respective terminals of one winding 293, 294 of a repeating coil290 located at the station 200 in the cab of the second locomotive. Theother winding |93, |94 of the repeating coil |90 has its terminalsconnected, respectively, to the conductors |02 and |03 of the linecircuit section |0I, this section being opencircuited, as shown, withthe locomotives arranged in tandem in the order indicated but beingprovided for use in the event the order of the locomotives is reversed,The repeating coil 290 includes a winding 29|, 292 having its oppositeterminals connected, respectively, to the conductors 205 and 206 of theline circuit section 204. These last-mentioned conductors also terminateat the respective terminals of one winding 343, 344 of the repeatingcoil 340 located at the station 300. The other winding 34|, 342 of thecoil 340` is arranged to be connected by the pair of conductors 305 and306 to the winding 313, 314 of the repeating coil 310 located at thestation 350. Finally, the other winding 31|, 312 of the repeater 310 isconnected by way of the pair of conductors 308 and 309 making up theline circuit section 301 to the opposite terminals of the telephone handset located at the station 350.

Eachof the telephone stations 00, |50, 200, 250, 300 and 350 comprises atransmitter and a receiver normally disconnected from the line circuitand preferably in the form of a hand set, and a manually operable switchwhich is operative to cause the associated transmitter and receiver tobe connected to the associated section of the line circuit. Morespecifically, there is provided at the rear car station 350 a hand set360 comprising a receiver 36| and a transmitter 362. This hand set alsohas embodied therein a manually operable switch comprising the springs364 and an actuating member in the form of a push button 363. Similarly,the apparatus at the station 300 comprises a hand set 330 havingembodied therein a receiver 33| and a transmitter 332, together with amanually operable switch including the springs 334 which normally occupythe open-circuited position illustrated in the drawings but may be movedinto engagement through the actuation of an associated push button 333.The last-mentioned station also includes a lockout relay 3 0 which formsmeans responsive to the operation of the switch in the hand set 360 forpreventing the transmitter 33| and the receiver 332 from being connectedtothe terminals of the repeater winding 34|, 342 when the line circuitis busy in connection with a call from the station 350 to one of thelocomotive cab stations. It will be noted that the circuit arrangementof the apparatus located at the station 300 is slightly different fromthat of the apparatus provided at the station 350 in that the manuallyoperable switch comprising the springs 334 is not effective directly toconnect the associated transmitter and receiver to the conductors of theline circuit section 304, but rather is effective to complete theoperating circuit for a second relay R320, which relay, in turn,performs the line switching functions. The relay R320 is also operativeto prevent a call from being initiated at the station 350 when the linecircuit is busy in connection with a call originated at the station 300.

The apparatus provided in each of the locomotive cabs is identical and,hence, it is believed that a brief description of the apparatus locatedin cab No. l, as illustrated in Fig. l, will suffice for the present,especially in View of the fact that the corresponding elements in cabNo. 2, as illustrated in Fig. 2, are identified by the same referencenumerals prefixed with the two hundreds digit rather than the onehundreds digit. As illustrated in Fig. 1, the apparatus in the iirstlocomotive cab at the station |00 comprises a hand set |40 havingembodied therein a receiver |4| and aV transmitter |42 together with amanually operableswtch comprising the springs |44 and the push button|43. Similarly, the apparatus at the station |50 comprises a hand set|10 including a receiver |1| and a transmitter |12 and having embodiedtherein a manually operable switch comprising the springs |14 which areunder the control of a push button |13. This station also includes adevice in the form of a relay RI 60 which operates in response to theactuation of the push button switch to connect the transmitter |12 andthe receiver |1| across the conductors |05 and |06 of the line circuitsection |04. Also included at the station |00 is a signal device in theform of a bell ringer |81 which comprises an operating magnet |89 andContact springs |88 under the control of the bell striker. This signaldevice includes an operating circuit which is independent of the linecircuit and is arranged to be completed in response to the actuation ofa push button switch |15 provided at the station |50. By thisarrangement, a person calling the station |00 from the station |50 maysignal the first-named station directly and withoutY affectingthe'signal device provided at the station 200. The signal device notedalso includes van alternative operating circuit, traced hereinafter,which is under the control of each of two relays R||0 and R|20. As willbe pointed out in detailA hereinafter, the relay R! |0, and also thecorresponding relay R2 l0 provided at the station 200, comprise meansresponsiveto the operation of either ofthe two push button switchesembodied in the apparatus at the station 300 and the station 353,respectively, for'completing the alternative operating circuits for thesignal ydevices |81 and-281 locatedprespectively, at the stations |00and-200. The signal devices noted are deenergized, following rtheirenergization, through the provision of a' relay R|30 at the sta- Vtion|00 and a corresponding relay R230 at the station 200, which relays arerespectively arranged to respond to the actuation of the manuallyoperable push'button switch provided at the respective two stations orto thel operation of the corresponding relay at the other station.

rI-he alternative operating circuit for the signal device |81'may alsobecompleted through the operation of the relay Rl20but, with the cabsarranged inthe order described above, this relay is not susceptible ofbeing energized. At the station 263, however, the'corresponding relayR220, which is arranged to complete the alternative operating circuitfor the signal device 281, operates in response to the actuation of asecond manually operable switch |80 provided at the station 00. Therelay R|30 provided at the station |00 not only functions to cause thesignal device |31 to be deenergized under certain conditions, but isalso' operative to connect the transmitter M2 and the receiver |ll|across the line conductors |65 and |03 of the line circuit section |04.Similar" functions are performed` by the corresponding relay R230provided at the' station 200.

Current for energizing the various relays indicated in'the drawings andthetwo signal devices is obtained from a common source which,preferably, comprises the storage battery conventionally 'Y embodied asstandard equipment in each of the locomotives. In order to facilitate adescription of the circuits involved, this source'has not beenillustrated inthe drawings, but it is explained that the positiveterminal of the source is connected to all circuit conductors indicatedas terminating at ground whereas the negative terminal of the source isconnected to the various negative terminals illustratedy in thedrawings. Sinceeach of the'transmitter and receiver cells embodied inthe various hand sets may be of any standard' commercial construction,these elements have been only schematically illustrated in the drawings.It is pointed out,.however, that reach of the transmitters |02, |12,242,212, 332

and 332 is preferablyv of the self-powered type which obviates thenecessity-of `using an auxiliary current source for voice frequencycurrent transmission. Several Vwell-known transmitters of this type arecommercially available. In brief, this type of transmitter usuallycomprises a diaphragm f which is connected by means of a sturdy but verylight connecting rod tovantV armature balanced betweenV the poles of yanextremely powerful permanentr magnet. In its operation, and when soundwaves impinge upon thel diaphragm, the diaphragm vibrates in accordancewith these waves to transmit the-vibrations'to the armature. Thearmature, in turn, vibrates and sets up a induced voltage thus generatedvaries in ampli- 5 tude and frequency in accordance with the amplitudeandintensityof the input sound waves.

As indicated above, with the arrangement described, it is only possiblefor the locomotive cab stations to be called. Referring now to the 0p--10 eration of the apparatus to complete a connectionbetween the station350 and oneof the two stations |00 and 200, it is pointed out that thecall is initiated in response to the actuation of the button 333embodied in the hand set 360. 15

This results in the completion of a simplex circuit for energizing thelockout relay R3|0 provided at the station 360, one branch of thiscircuit extending from ground on the conductor 365 by way of the closedswitch springs 364i, the=20 conductor 366, the winding 313, theconductor 305, RAS i3, RC3 I4, RA323 and through the winding of R3|0 tobattery, and the other branch extending from the conducto-r 366 by wayof the Winding 311|, the line conductor 306, RA3|6525 RAMI', and RA324and through the winding oi R3|0 to battery. The relay R3|0, uponoperating, opens, at RA3I2, a point in the operating circuit for R320,thereby to prevent the transmitter 332 and the receiver 33| at thestation-130 V366 from being connected to the conductors of the linevcircuit in response to the operation of the push button 333. At itsarmatures RA3|2 and RA3|5 and their respective associated armaturesRA3|3 and RA3|3, the relay R3|0 connects' -35 the line conductors 305and 306 to the opposite terminals of the repeater coil winding 32E, 322.At RA3|3 and RCSM, the relay R3|6 opens a point in its originaloperating circuit, but only after an alternative branch circuit hasbeen4 com-i140 pleted, by way of RA3l3, RA3|2 and the Winding 34|, formaintaining itself energized.

At RA3| the relay R3|0 completes a simplex `circuitfor energizing R2|6located at the station 200,'one branch of this circuit extending-1215from ground at theV armature noted by way of the conductor 3|8, theWinding 323, the line conductor 205, the winding 23|, the switch springs285 and 286, RA233, the winding of R2!!! and the conductor 2|5 tobattery. The other branchiio of the simplex circuit extends from groundat RA3|| by Way of the conductor 396, the winding 334, the lineconductor 206, the winding 292, the switch springs 285 and 286, RA233,the winding of R2|0 and the conductor 2|5 to battery. Thefiffi relayR2|0 now operates to complete, at RA2| i, the above-noted alternativecircuit for energizing the signal device 281, which circuit extends fromground as applied to the conductor 2|6 by Way of RAZII, the winding ofthe magnet 289 andf` the springs 238 to battery. Through thecircuitinterrupting action of the springs 230, the signal device 281 iscaused to operate to give an audible indication that the station 200 isbeing called.

`The` relay REW: upon Opelng, also functionsli' to complete a simplexcircuit for energizing Ri i0 embodied in vthe apparatus provided at thestation |00. One branch of this circuit extends from ground on theconductor 2|1 by Way of the upper winding of R230, the conductor2|6,-'70

RC2M, RAZIE, the conductor 2|9, the switch springs 283 and 282, thewinding 233, the line conductor |05, the winding |9|, the switch springs|35 and |86, RAl33, the winding of Ri i0 `and the-conductor ||5-tobattery. The otheri'Y-l branch of this circuit is quite similar tothat just described but extends by way of the winding 294, the lineconductor |06 and the winding |92 rather than by way of the winding 233,the conductor |05 and the winding I9I. Due to the relatively highresistance of the winding of RIIO, the relay R230 does not operate whenits upper winding is energized over the above-traced circuit. The relayRI I0, however, operates to complete, at RAIII, the above notedalternative circuit for energizing the signal device |81, this circuitextending from ground on the conductor I I6 by way of RAI I I, thewinding of the magnet and the contact springs |88 to battery. Due to thecircuit interrupting action of the contact springs |88, the signaldevice |81 operates to give an audible indication that the station |00is being called.

Obviously, the above-described operations occur each time the pushbutton 393 embodied in the hand set 360 is depressed. If desired, thispush button may be actuated in accordance with a coded signalselectively to indicate which of the two stations |00 and 200 is beingcalled. It may happen that the trainman who initiates the call desiresto converse with the engineers in both locomotive cabs, in which case acoded signal indicating the non-selective call may be transmittedthrough proper manipulation of the push button 363. Following operationof the push button 363 to signal the desired station, this button isheld depressed to maintain R3|0 operated. With this relay operated theconductors 305 and 306 of the line circuit section are maintainedconnected to the opposite terminals of the repeating coil winding 34|,342 andthe operating circuit for R320 is held open.

Assuming, for the moment, that the call is intended for the station 200,the desired connection is established when the call is answered at thisstation by actuation of the button 243 ernbodied in the hand set 240 tomove the contacts carried by the springs 244 into engagement. Inresponse to this operation, acircuit is completed for energizing R230,this circuit extending from ground on the conductor 2I1 by way of theupper winding of R230, the conductor 223, the switch springs 244, theresistor 222 and the conductor 2|5 to battery. The resistor 222 is acurrent determining resistor and the value thereof is selected so thatthe full rated current for the upper winding of R230 is passed throughthis winding when the springs 244 are closed. Hence, R230 is caused tooperate when energized over the abovetraced circuit and, upon operating,opens, at RA233, a point in the above-traced operating circuit for R2I0.The relay R2|0 now restores to open, at RAZI I, the alternativeoperating cir- .cuit for the signal device 281. At RA2|2 and RC2|4, therelay R2I opens a point in the simplex circuit, traced above, forenergizing RI|0, causing the last-mentioned relay to restore to open, atRAI I I, the alternative operating circuit for the signal device |81.Thus, it will be seen that, when the push button switch incorporated inthe Hand set 240 is operated, the two signal devices |81 and 281 aredeenergized. At RA232, the relay R230 completes a simplex holdingcircuit for itself, one branch of this circuit extending from ground, atthe operated armature RASI I, by way of the conductor 3I8, the winding343, the line conductor 205, the winding 29|, the switch springs 285 and286, RA232, the lower winding of R230 and the conductor 2|5 to battery.The second branch of this circuit is substantially similar to that justtraced but extends by way of the winding 344, the line conductor 206 andthe winding 292 rather than by way of the winding 343, the conductor 205and the winding 29| as included in the rst branch of the circuit, tracedabove. Thus, the relay R230 is held operated independently of the pushbutton 243 so long as the push button 363 is held dev pressed.

When the relay R230 operates, it also functions to complete, at RA23I, apath for connecting the transmitter 242 and receiver 24| across the lineconductors 205 and 206 of the line circuit section 204, this path beingmore or less obvious and including the conductors 246 and 241. As thusconnected, a talking circuit, comprising the line circuit sections 204,304 and 301 and the repeating coils 340 and 310 is completed between thestation 200 and the station 350.

Before describing the release of the connection and in order to give afull description of the operation of the apparatus, it will now beassumed that the call is answered at the station |00 rather than at thestation 200. In this case, the push button |43 is depressed by theanswering party to complete a circuit for fully energizing the upperwinding of R|30, this circuit extending from ground as applied to theconductor |I1 by way of the upper winding of R|30, the conductor |23,the switch springs |44, the resistor |22 and the conductor |I5 tobattery. Upon being energized over the above-traced circuit, RI30operates to open, at RA|33, a point in the above-traced circuit forenergizing RIID, causing this last-mentioned relay to restore tointerrupt, at RAI I I, a point in the alternative operating circuit forthe signal device |81. At RAI3 I, the relay RI30 completes a pathcomprising the conductors |46 and |41 for connecting the transmitter |42and the receiver I4| across the line conductors |05 and |06 of the linecircuit section |04, thereby to complete a talking circuit including thesection |04, the repeater 290, the section 204, the repeater 340, thesection 304,

the repeater 310 and the section 301, which extends between the stations|00 and 350. At RA|32, the relay RI30 completes a simplex circuit forenergizing its lower winding in series with the upper winding of R230,one branch of this circuit extending from ground on the conductor 2|1 byway of the upper winding of R230, the conductor 2|8, RC2I4, RA2I2, theconductor 2 I9, the switch springs 283 and 282, the winding 293, theline conductor |05, the winding |9I, the switch springs |85 and |86,RAI32, the lower winding of RI30 and the conductor ||5 to battery. Theother branch of the circuit is similar to that just described, butincludes the winding 294, the line conductor |06 and the winding |92rather than the winding 293, the line conductor |04 and the winding ISI.The relay R230 operates when its upper winding is energized over theabove-traced circuit to interrupt, at RA233, a point in the above-tracedoperating circuit for R2|0, causing the last-mentioned relay to restoreto open a point in the alternative operating circuit for the signaldevice 281. At RA232, the relay R230 completes the above-traced holdingcircuit for itself. Thus, R230 remains operated for the duration of theconversation and, in its operated position, holds the receiver 24| andthe transmitter 242 connected across the conductors 205 and 206 of theline circuit section 204. Also, with this relay operated, R2I0 circuit.'Hence, if the push button 243` is released Z the deenergization2,168,880. :is maintained in its restoredposit'io'n .so lthat the f.signal device 281 is prevented from-ringing.

From the foregoing description it will readily c'be .apparent that thecall as initiated at the station 350 .maybe answered ateither or both of`.the stations .|00 and 20|).- If the call is simultaneously answered ateach of thesetwo stations, the relay R230 at the station 200 functionsimmediately to cause the restoration .of R2|0 and of the signal device2181, and 'the relay-R|30l at the station |00 functions to cause thevimmediate restoration of Rl |0 and the .deenergization of the signaldevice |81. The operation of each of theY relays R|`30. and-R230 .causesthe associated transmitter and receiver to be connected to theconductors of the line circuit.

The release of a talking connection as established in the mannerdescribed above is dif- .,ferent dependingv upon which of the stations|00 Thus, if it at .the staand 200 is the answering station. be assumedthat thecall is answered tion 200, the relay R230, upon operating,immediately completes the above-traced holding circuit for itself, whichcircuit extends from ground at RA3|| of the operated relay R340.. SinceR3|0 is no1'l deenergized until the connection is released` at .thekstation 350, the relay R230 will beheld operated independently of its.operating while the .push button 353 isr still depressed, thetransmitter 242 and the Vreceiver 24| atv the station 200remainconnectedto the line circuit section 204 by virtuefof the continued energizationyof R230. When, however,

the push button 363 is released, the operating circuit for R3 |0'isopened at the springs364 causing this relay to restore. Uponrestoring,R3|0 reprepares, atRA3l2, the operating circuitfor R320;opens, at RA3| 2 and RA3|5 and their respective associated armaturesRA3|3 and RASIB, a point in the talking connection, as described above;and interrupts, at RA3| a point in the above-traced holding circuit forR230. If the push button 243 has been released prior to the. release yofthe push button 363, the relay R230 now restores to disconnect,

24| andv the transmitter conductors. 205. and 200 At its armaturerestoring, repre pares thev operating circuitlforRZlll. Following thisoperation, the connection is entirely released and the Systemisin'connection for further use in connection vwith another call.

If the calll is answered at the station '|03 and the answering partyreleases the push button |43 before the callingk partyreleases the push.button 353, therelay R|33 restores to disconnect the transmitter |42 andthe receiver |45 fromacross the conductors of the line section |34, andto reprepare, at RA|33,the operating circuit for R| lil. releases the.push button 353 to open. the operating circuit for R3! @,this lastmentioned relay restores to open a point in the talking circuit; toreprepare, at RA3l2, the operating circuit for R320; and to interrupt,at RAS! l, a point in the holding circuit for R233; TheA relay R233 nowrestores to disconnect, at RAZSH, the transmitter 242 and the receiver24 Yfrom across theconductors of the line circuit section 234 ,and .toreprepare, at RA233, the operating circuit for R25 0. Thus, theconnection is completely released.

It will be apparent that, if the call is answered at RA23|, thereceiver242 from across the of the line circuit section 204.

, at the station i'and the calling party at the ground as appliedThereafter,'and whenthe calling partyV station 37505releases the pushbutton 333 before the answering 4party releases the push button |43, theorder of the operations is the reverseof that just described. -Morespecifically, when the button 363 is released, the operating circuit foru R3|0 is interrupted at the springs 364 whereupon thisrrelay restoresto open the holding circuit for R230. Thereafter and when the pushbutton |43 is released, the operating circuit for -Rl30 is opened at thesprings |44 and this relay restores. It is apparent, therefore, that therelease of the connection as established between the stations .|03 and350 is in no way affected by the order in which the push buttons |43 and363 are released.

The operation "of the apparatus following the initiation. of a call atthe station 300 is identical that just described insofar as theapparatus at the stations 33 and 200 is concerned, but differs therefromin-that the apparatus at the station 333 is locked out and the apparatusat the station 533 is connected .to the line circuit. Thus, when thepush button 333 is depressed to initiate a call at the station 303, acircuit is completed for energizing R323, this circuit extending from ofthe switch springs 333, the conductor 327i', RA3|2 and through thewinding of R323 to battery. The relay R323 now operates and, at RA32l,applies ground to the conductor 3|8, thereby to cause the energizationand operation of both of the signal .devices E87 and 231 located,respectively, at the stations |00 and 200, in the exact manner set forthabove. At its armatures RA322 and RA325, the relay R320 connects theconductors 323 and 333 to the respective terminals of the repeatertransmitterl 332v and the receiver `33| are connected across thiswinding Yto prepare a talking circuit to one or both of the 4twostations .Stil and 200. At RA323 and-RASEthe relay opens pointsin-theaboveftraced operatingcircuit ior R3t0', whereby this relay ispreventedrom oper.- ating in response to actuation of the push button333.50 long as the push buton333 pressed. At RA323and forming the line.circuit nectedirom the repeater coil k343.

The modev of operation of thel apparatus provided `at thestations v|33and 230..:Eollowingthe initiation of a callat'the station .330 is, aswasy pointed .out above, exactlyfthey same as that .set

forth previously with reference to a call initiated at the station30,and` this is true irrespective the station 200, or both. Also, vthe modeof dis connecting the apparatus l.from theline circuit to release theequipmentcr furtheruse is similar to that describedabove,differingtherefrom only in that ground is removed from theconductor 3! 3to open the holding circuit for R233. following .the release of the pushbutton 333 to open the operating circuit for R323,V When R320 restores,it not only removes ground from. the conductor 3i 3, but alsodisconnects the receiver 33H and the transmitter332 from across thewinding33l 332 of the repeating coil 343 and repreparesthe operatingcircuit forR3 0, so. that the last-mentioned relay may be energized inkresponse, to the ,initiation of a call at the station 350.

As indicated above, it is possible for two of the train attendants tohold intercab communication in either of the two locomotive cabs. Thus,a trainman at the station ldmay initiate a call directly to the ,station|30, without in anyway aiecting the apparatus located atthev otherstatothe conductor 3&6 byV Way l coil winding 34H, 332, whereby thetions, by actuating the push button |15 of the manually operable switchcomprising the springs |16. This operation serves to complete theoperating circuit for the signal device |81, which circuit extends fromground as applied to the conductor |62 by way of the switch springs |16,the conductor |64, the winding of the operating magnet |89 and thecontact springs |88 to battery. The resulting operation of the signaldevice |81 gives an audible indication that the station |00 is beingcalled. The call is answered at the station |00 in the usual manner bydepressing the push button |43 to complete the above-traced circuit forenergizing the upper winding of R|30. The relay R|30 now operates toconnect, at RA|3|, the receiver |4| and the transmitter |42 of the handset |40 across the conductors |05 and |06 of the line circuit section|04. At RA|33, the relay R|30 opens a point in the operating circuit forR||0, whereby the signal device i81 is prevented from being energized inresponse to the initiation of a call at one of the stations 200, 300 and350. The connection is completed when the push button |13 embodied inthe hand set |10, provided at the station |50, is depressed, thisoperation serving to complete a circuit for energizing R|60.Specifically, this circuit extends from ground as applied to theconductor |62 by way of the switch springs |14, the conductor |53 andthrough the winding of R|60 to battery. The relay R|60, upon operating,completes, at RA|6|, a path comprising the conductors |11 and |18 'forconnecting the transmitter |12 and the receiver |1| across the lineconductors |05 and |06 of the line circuit section |04.

To release a connection as established between the stations '|00 and |50in the manner set forth in the immediately preceding paragraph, it isonly necessary that the two push buttons |43 and |13 be released. Whenthe first mentioned button assumes its normal position, the operatingcircuit for R|3 0 is opened, causing this relay to restore to disconnectthe transmitter |42 and the receiver |4| from across the conductors ofthe line circuit section |04. Similarly, when the push button |13 isreleased, the operating circuit for R|60 is interrupted at the switchsprings |14, causing this relay to restore to open, at RAI'BI, a pointin the path by way of which the receiver |1| and the transmitter |12 areconnected across the conductors |05 and |06.

Since, as was pointed out above, the apparatus located in the secondlocomotive cab is identical in all respects with that provided in thefirst locomotive cab, it will be understood that a connectionmay beestablished between the stations 200 and 250 on a call from the latterto the former and, further, that the operations involved in completingand releasing such a connection are identical with those just describedwith reference to the establishment of a connection on a call from thestation |50 `to the station |00.

The initiation of a call to the station 200 located in the secondlocomotive cab from the station |00' located in the first locomotive cabinvolves the use of the non-locking key switch |80. More specifically,when this switch is operated to its off-normal position, a simplexcircuit is completed for energizing R220, one branch of this circuitextending from ground on the conductor ||1 by way of the switch springs|84 and |85, the winding IBI, the conductor |05, the Winding 293, theswitch springs 282 and 283,

the conductor 2|9, RA2l2, RC2|3 and through the winding of R220 tobattery as applied to the conductor 2|5. The other branch of thiscircuit is similar to that just described, but extends by way of thewinding |92, the conductor |06, and the winding 294 rather than by wayof the winding |9|, the conductor |05, and the winding 283. The relayR220, upon operating, completes, at RA22|, the above-traced alternativeoperating circuit for the signal device 281, which device now operatesto give an audible indication that the station 200 is being called.Following operation of the switch in accordance with the coded ringidentifying the station 200', this switch ls released to interrupt theabove-traced operating circuit for R220, whereby this relay is caused torestore to open the operating circuit for the signal device 281. Atalking connection is established by depressing the two push buttons |43and 243. When the button |43 is depressed, the above-traced operatingcircuit for R|30 is cornpleted at the switch springs |44, causing thisrelay to operate to complete, at RA|3|, the path for connecting thereceiver |4| and the transmitter |42 across the conductors of the linecircuit section |04. When the push button 243 embodied in the hand set240 is depressed, the operating circuit for R230 is similarly completedat the springs 244, whereby this relay is caused to operate to complete,at RA23I, the path for connecting the transmitter 242 and the receiver24| of the hand set 240 across the conductors of the line circuitsection 204. So long as the two push buttons noted are held inV theirrespective depressed positions, a talking circuit is completed betweenthe two stations |00 and 200, which circuit specifically comprises theline circuit section |04, the repeating coil 290', and a portion of theline circuit section 204. In order to release a connection as set up inthe manner just described, it is only necessary for the two parties torelease the two push buttons |43 and 243, thereby to open the respectiveoperating circuits for the relays RI 30 and R230. When these relaysrestore, the transmitters and receivers embodied, respectively, in thetwo hand sets located at the respective stations are disconnected fromthe line circuit and the apparatus is in condition for further use.

The operation of the apparatus to set up a talking circuit Y between thetwo stations |00 and 200 on a call from the latter to the former is, ingeneral, quite similar to that set forth in the preceding paragraph. Inthis case, however, the non-locking key switch 280 is operated to itsolf-normal position to eiect operation of the signal device |81 locatedat the station |00. When this key switch is moved to its off-normalposition, a simplex circuit is completed for energizing RI ||0, onebranch of this circuit extending from ground on the conductor 2|1 by wayof the switch springs 28| and 282, the winding 283, the line conductor|05, the winding |9|, the switch springs and |86, RA|33, and through thewinding of RI |0 to battery as applied to the conductor ||5. The otherbranch of this circuit is similar to that just described, but extends byway of the winding 294, the line conductor |06 and the winding |82rather than by way of the winding 293, the conductor |05 and the winding|9|. When RI |0 operates, it completes, at RAI the above-tracedalternative operating circuit for the signal device |81 causing thisdevice to give an audible indication that the station |00 is beingcalled. The talking circuit between the two stationsis identical withthat briefly described in the preceding paragraph and is completed inthe same manner, namely, through the operates it opens, Aat RA|33, apoint in the ab0-ve-;

traced operating circuit for R| I0, thereby to cause RI |0 to restore toprevent further operation of the signal device |81. The interruption ofthe talking circuit to release the apparatus is accomplished insubstantially the manner described above, that is, by releasingthe twopush buttons |43 and 243 to cause the restoration of the two relaysR|3i0` and R230. As pointed out above, when R| restores, the path forconnecting the receiver |4| and the transmitter |42 across theconductors |05 and |06 is in-terrupted at RA|3| and, similarly, whenR230 restores, the path connecting the transmitter 242 and receiver 24|across the line conductors 205 and 206 is opened at RA23|. From theforegoing description, it will be apparentthat the position of the twolocomotives may be transposed without in any waydisrupting the operationof the systenror in any way modifying its mode of operation. thelocomotive having embodied therein the apparatus illustrated in Fig. 2may be employed as the rst locomotive and the'locomotive having embodiedtherein the apparatus illustrated in Fig. 1 may be employed as thesecond locomotive.

In this case, however, the line circuit section |0| will effectively beconnected in the line circuit and the line circuit section |04 `will beopencircuitedin the exact manner illustrated for the section |0I.Otherwise, the apparatus located at the station 200 will operate Vin themanner set forth above with reference to the apparatus located at thestation |00, whereas-the apparatus at the last-mentioned station willoperate in the exact manner set forth above with reference to thatlocated at the station 200.v

While there has been described what is at present considered to be thepreferred embodiment of the invention, it Vwill be understood thatvarious modifications may be made therein, and it is contemplated tocover in the appended claims all such modifications'as fall within thevtrue spirit and scope of the invention.

I claim:

l. In'a signalling system, a plurality of signallingl stations,U a linelcircuit interconnecting said stations, a signal device at each ofcertain of said stationsa switch at each of said stations, meansresponsive to the operation of one of said switches forr causing theenergization oi all of said signal devices,rand means responsive to theoperation of another of said switches for causing the deenergization ofVall of said signal devices.

2. In ay telephone system, a plurality of telephone stations eachcomprising a transmitter and a receiver, a line circuit interconnectingsaid stations, a signal device at each oi certain of 5, said stations, aswitch at .each of said stations,

each of said switches being operative to connect the associatedtransmitter and receiver to said line circuit, means responsive to theoperation of one of said switches for causing the v energization of aplurality of said signal devices,

and means responsive to the operation of another of said switches for.causingthe deenergiza-v tion of; said .plurality of signal devices.

3..In atelephone system, a plurality of tele- .phone stations eachcomprising a transmitter More specically,

and a receiver, a line circuitinterconnecting said stations, a signaldevice at each of certain. of said stations, a switch at .each of saidstations, each of said switches being operative to connect theassociatedy transmitter and receiver to said line circuit, meansresponsive to the operation ofthe switch at a particular calling one ofsaid stations for causing Vthe energization of all of said signaldevices, and means responsive to the operation of the switch at ananswering one of said stations for causing the deenergizaticn of all ofsaid signal devices.

4. In a telephone system, a plurality of telephone stations eachcomprising a transmitter and a receiver, a line circuit interconnectingsaid*r means responsive to the operation of the switch at a particularcalling one of said stations for preventing the transmitter and receiverat a second of said stations from being connected to said line circuit,means also responsive to the operationgof said last-named switch forcausing the energization of yallof said signal devices, and meansresponsive to the operation of the switch at an answering one ofI saidstations for causing the deenergization of all of said signal devices.

5. Ina telephone system, a plurality of telephone stationseach-comprising a transmitter and a receiver, a line circuitinterconnecting said stations, a signal device at each of certain ofsaid stations, a switch at each of said stations, a relay at one of saidstations operative in response to the operation of the associated switchfor connecting the associated transmitter and receiver to said linecircuit, an operating circuit for said relay, means at each of the otherstations controlled by the respective associated switches for connectingthe respective associated transmitters and receivers to said linecircuit, a lockout relay cuit in response to the operation of the switchat a particular calling one of said stations, means responsive. to theoperation of said lockout relay for causing the energization of. all ofsaid signal devices, and means responsive to the operation of the switchat an answering one of said stations for causing the deenergization ofsaid signal devices.

6.In a telephone system, a plurality of telephone stations eachcomprising ka transmitter and a receiver, a line circuit interconnectingsaid stations, a signal device at each of certain of said stations, aswitch at each of said stations, a relay at one of said stationsoperative in response to the operation of the associated switch forconnecting the associated transmitter and receiver to said line circuit,an operating circuit for said relay, means at each of the other stationscontrolled by the respective associated switches for connecting therespective associated transmitters and receivers to'said line circuit, alockout relay operative to open a point in said operating circuit inresponse to the operation of the switch at a particular calling one ofsaid stations, a plus rality of relays each associated with. one ofsaidV 4cause the deenergization of said 5 operating circuit of 5 forpreventing 70 said line sively energized in response to the operation ofsaid lockout relay, and means responsive to the operation of a switch atan answering one of said stations for altering said circuit connectionsto plurality of relays.

7. In a telephone system a pair of telephone stations each comprising atransmitter and a receiver, a line circuit interconnecting said stations10 and comprising a plurality of conductors, a manually operable switchat each station, means at each station controlled by the associatedswitch for connecting the associated transmitter and receiver to theconductors of said line circuit, a

signal device, a second manually operable switch at one of saidstations, a circuit independent of said line circuit and includingcontacts embodied in said second switch for energizing said signaldevice, an alternative circuit for energizing said zo-signal device, arelay at the other of said stations operative to complete saidalternative circuit, and means responsive to the operation of the switchat said other station for preventing said relay from operating tocomplete sald alternative cirl Cuit.

lrelay at each station including contacts for connecting the associatedtransmitter and receiver to the conductors of said line, an operatingcircuit individual to each relay, a manually operable switch at eachstation for completing the the associated relay, a signal device at oneof said stations, a second manually operable switch at the other of saidstations, a circuit independent of saidline circuit and includingcontacts embodied in said second switch Oilfor energizing said signaldevice, an alternative circuit for energizing said signal device, asecond relay at said one station and operative to complete saidalternative circuit, and means comprising the iirst-named relay at saidone station said second relay from operating to complete saidalternative circuit when the transmitter and receiver` at said onestation are connected to the conductors of said line circuit,

9. In a telephone system, a pair of telephone stations each comprising atransmitter and a receiver, a line circuit interconnecting said stationsand comprising a plurality of conductors, a manually operable switch ateach station, means at each station controlled by the associated switch5 for connecting the associated transmitter and receiver to theconductors of said line circuit, a signal device, a second manuallyoperable switch at one of said stations, a circuit independent of saidline circuit and including contacts embodied .in said second switch forenergizing said signal device, an alternative circuit for energizingsaid signal device, a relay at the other of said stations operative tocomplete said alternative circuit, an operating circuit for said relay,said operat- 65ing circuit including at least one of said lineconductors, means responsive to the operation of the switch at the otherof said stations for preventing said operating circuit from beingcompleted, an additional telephone station associated with circuit, anda switch at said additional station operable to complete said operatingcircuit only when the switch at said other station is not operated.

10. In a telephone system, a pair of telephone 75 stations eachcomprising a transmitter and a receiver, a line circuit interconnectingsaid stations and comprising a plurality of conductors, a manuallyoperable switch at each station, means at each station controlled by theassociated switch for connecting the associated transmitter and receiverto the conductors of said line circuit, a signal device,A a secondmanually operable switch at one of said stations, a circuit independentof said line circuit and including contacts embodied in said secondswitch for energizing said signal device, an alternative circuit forenergizing said signal device, a relay at the other of said stationsoperative to complete said alternative circuit, an operating circuit forsaid relay, said operating circuit including at least one of said lineconductors, means responsive to the operation of the switch at the otherof said stations for preventing said operating circuit from beingcompleted a pair of additional telephone stations associated with saidline circuit, a manually operable switch at each of said additionalstations, the switch at one of said additional stations being operativeto complete said operating circuit only when the switch at said otherstation is not operated, and means responsive to the operation of theswitch at the other of said additional stations for completing saidalternative circuit independently of the position of the switch at saidother station.

l1. In a telephone system, a pair of telephone stations each comprisinga transmitter and a receiver, a line circuit interconnecting saidstations and comprising a plurality of conductors, a manually operableswitch at each station, means at each station controlled by theassociated switch for connecting the associated transmitter and receiverto the conductors of said line circuit, a signal device, a secondmanually operable switch at one of said stations, a circuit independentof said line circuit and including contacts embodied in said secondswitch for energizing said signal device, an alternative circuit forenergizing said signal device, an additional telephone stationassociated with said line circuit, a manually operable switch at saidadditional station, and means responsive to the operation of saidlast-named switch for completing said alternative circuit.

12. In a telephone system, a pair of telephone stations each comprisinga transmitter and a receiver, a line circuit interconnecting saidstations and comprising a plurality of conductors, a manually operableswitch at each station, means at each station controlled by theassociated switch for connecting the associated transmitter and receiverto the conductors of said line circuit, a signal device, a secondmanually operable switch at one of said stations, a circuit independentof said line circuit and including contacts embodied in said secondswitch for energizing said signal device, an alternative circuit forenergizing said signal device, a relay at the other of said stationsoperative to complete said alternative circuit, an operating circuit forsaid relay, said operating circuit including at least one of said lineconductors, means responsive to the operation of the switch at the otherof said stations for preventing said operating circuit from beingcompleted, an additional telephone station associated with said linecircuit, a switch at said additional station, and means responsive tothe operation of said last-named switch for completing said alternativecircuit independently of the position of the switch at said otherstation.

13. In a telephone system, a telephone station comprising, incombination, a signal device, a transmitter, a receiver and a manual-lyoperable switch, a line extending'to said station and including a pairof conductors, a relay operative in response to the application of apredetermined potential to one of said conductors to cause theenergization of said signal device, and means comprising a second relayoperative in response to the operation of said switch for causing thede'energization of said first-named relay and for connecting saidtransmitter and receiver to said line.

14. In a telephone system, a telephone station comprising, incombination, a signal device, a transmitter, a receiver and a manuallyoperable switch, a line extending to said station and including a pairof conductors, a circuit for energizing said signal device, a relayoperative to complete said circuit, an operating circuit for said relay,said operating circuit, including one of the conductors oi said linecircuit and being adapted to be completed when a predetermined potentialis applied to said one conductor, a second relay operative in responseto the operation of said switch to connect said transmitter and receiverto said line, and contacts controlled by said second relay forinterrupting the operating circuit for said first-named relay when saidswitch is operated.

15. In a telephone system, a telephone station comprising, incombination, a signal device, a transmitter, a receiver and a manuallyoperable switch, a repeater comprising a pair of windings, a lineextending to said station, said line including a pair of conductorsrespectively connected to the terminals of one of said windings and apair of conductors respectively connected to the terminals of the otherof said windings, means responsive to the application of a predeterminedpotential to one conductor of one of said pairs of conductors forcausing the energization of said signal device, means responsive to theapplication of said predetermined potential to one conductor of theother of said pairs of conductors for also causing the energization ofsaid signal device, and means responsive to the operation of said switchfor causing the deenergization of said signal device only when energizedthrough theoperation or said rst-named means.

16. In a telephone system, a telephone station comprising, incombinaton, a signal device, a transmitter, a receiver and a manuallyoperable switch, a repeater comprising a pair of windings, a lineextending to said station, Said line including a pair of conductorsrespectively connected to the terminals of one of said windings and apair of conductors respectively connected to the terminals of the otherof said windings, means responsive to the application of a predeterminedpotential to one conductor of one of said pairs of conductors forcausing the energization of said signal device, means responsive to theapplication of said predetermined po-tential to one conductor of theother of said pairs of conductors for also causing the energization ofsaid signal device, means responsive to the operation oi said switch forcausing the deenergization of said signal device only when energizedthrough the operation of said rst-named means, a second manuallyoperable switch at said station, said second switch being operative toapply said predetermined potential to one of the conductors of said onepair of conductors without causing the operation of said signal device.

17. In a telephone system, a plurality of telephone stations eachcomprisingY a transmitter and a receiver, a line circuit interconnectingsaid stations, a signal device at each of certain of said stations, .andcontrol apparatus located at each of said stations.; said controlapparatus, said signal devices, and said line circuit being so connectedand arranged that all of said signal devices may simultaneously beenergized from certain of said stations, said signal devices mayselectively be energized from others of said stations, and talkingconnections including said line circuit may be established between atleast a portion of said telephones.

18. In a telephone system, a plurality of telephone stations eachcomprising a transmitter and a receiver, a line circuit interconnectingsaid stations, a signal device at each of certain of said stations, atleast one switch at each of said sta.- tions, and control .apparatuslocated at each of said stations; said control apparatus, said signaldevices, said line circuit and said switches being so connected andarranged that all of said signal devices are simultaneously energized inresponse to the operation of certain of said switches, said signaldevices are selectively and individually energized in response to theactuation of others of said switches, and talking connections includingsaid line circuit may be established between at least a portion of saidtelephones.

19. In a telephone system for use on board a train comprising aplurality of interchangeable vehicles, a pair of telephone stations ineach of certain of said vehicles, a single telephone station in each ofothers of said vehicles, said stations being adapted to beinterconnected by a line circuit extending therebetween and eachcomprising a transmitter, a receiver and control apparatus; the controlapparatus, the transmitter and the receiver at each of the two stationsin each vehicle having a pair of stations being so connected andarranged that the positions of the vehicles having two stations may beinterchanged -in the train without interfering with the operation ofsaid system.

20. A train telephone system comprising a terminal station located atone point on the train, a plurality of telephones located at other anddifferent points on said train, a line circuit extending through thetrain and adapted to interconnect said telephones and said terminalstation, a signal device at said terminal station,

a switch associated with one of said telephones.,

means responsive to operation of said switch for connecting said onetelephone to said line, andv means also responsive to operation of saidswitch for causing the operation of said signal device.

21. A train telephone system comprising a terminal station located atone point on the train, a plurality of telephones located at other anddifferent points on said train, a line circuit extending through thetrain and adapted to interconnect said telephones and said terminalstation, a signal device at said terminal station, a switch associatedwith one of said telephones, means responsive to operation of saidswitch for energizing said signal device, and means also responsive tooperation of said switch for preventing any telephone other than saidone telephone irom being connected to said line.

22. A train telephone system comprising a terminal station located atone point on the train, ,a plurality of telephones located at other anddifferent points on said train, a line circuit extending through thetrain and adapted to interconnect said telephones and said terminalstation, a signal device at said terminal station, .a switch associatedwith one of'said telephones, means responsive to operation of saidswitch for connecting said one telephone to said line, means alsoresponsive to operation of said switch for causing the operation of saidsignal device, and means also responsive to operation of said switch forpreventing any telephone other than said one telephone from beingconnected to said line.

23. In a telephone system for use in a train comprising a plurality ofinterchangeable vehcles, a plurality of telephone stations in each of atleast a portion of said vehicles, said stations being adapted to beinterconnected by a line circuit extending therebetween and eachcomprising a transmitter, a receiver and control apparatus; the controlapparatus, the transmitter, and the receiver at each of the stations ineach vehicle having a plurality of stations being s0 connected andarranged that the positions of the vehicles having a plurality ofstations may be interchanged without interfering with the operation ofthe system.

EDWARD S. PETERSON-

